Zone 4 Impedance Setting - Siemens 7SG164 Ohmega 400 Series Manual

7SG164 Ohmega 400 Series Applications
A B C
I + I
I
A B
A
AC
L OHM S L OHM S
AB BC
I
B
AC

3.2.6 Zone 4 Impedance Setting

The Zone 4 setting has an independent impedance range the line angle is the mirror image of the forward angle
and is not independently adjustable. The Zone 4 impedance element can be used to directly trip the relay or it
can be used with the scheme logic to provide reverse looking fault detection for protection blocking schemes.
The Zone 4 resistance setting for earth fault quad characteristics is set to give an adequate resistive cover to
allow for tower footing resistance and arc resistance. This setting is required in secondary ohms.
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